Pen



FIG. 1 shows a left side perspective view of my design for a pen;

FIG. 2 shows a perspective view thereof, with the pen tip retracted;

FIG. 3 shows a front elevational view thereof;

FIG. 4 shows a left side elevational view thereof;

FIG. 5 shows a rear elevational view thereof;

FIG. 6 shows a right side elevational view thereof;

FIG. 7 shows a top plan view thereof; and,

FIG. 8 shows a bottom plan view thereof. 

The ornamental design for a pen, as shown and described. 